1. Field of the Invention
The invention relates to a knuckle suited to be applied to a suspension unit for a vehicle such as a passenger car, a truck, a bus or the like.
2. Description of the Related Art
As suspension units applied to vehicles, suspension units of an independent suspension type that independently support left wheels and right wheels with a view to improving the grounding property of the wheels have been employed. For example, suspension units of a multi-link type, a double wishbone type, and a McPherson strut type are well known. Especially a suspension unit of the McPherson strut type is constructed such that a knuckle for rotatably supporting each wheel is coupled to a vehicle body side via a lower arm, and that an intermediate part of this lower arm or the knuckle and the vehicle body side are coupled to each other by a shock absorber. The suspension unit of the McPherson strut type is therefore simple in structure and advantageous in space saving and cost reduction.
A knuckle for use in a suspension unit that is made of an aluminum extrusion material as described in Japanese Patent Application Publication No. 8-324450 (JP-A-8-324450) has been proposed for the purpose of enhancing mass productivity and reducing manufacturing costs.
However, in this knuckle described in Japanese Patent Application Publication No. 8-324450 (JP-A-8-324450), part of a bearing mounting body, an upper suspension arm mounting arm, and a lower suspension arm mounting arm are constructed as a first member made of an aluminum extrusion material, and the rest of the bearing mounting body and a tie rod mounting arm are constructed as a second member made of an aluminum extrusion material. The first member made of the aluminum extrusion material and the second member made of the aluminum extrusion material are so coupled as to be superimposed on each other in the direction of a central axis of a bearing. The knuckle is thereby constructed.
In the knuckle thus constructed, especially in the former one of the members, that is, the first member made of the aluminum extrusion material, there is caused a problem in that the number of man-hours increases as a result of the need to cut the extruded extrusion material by means of water injection, laser beams, or the like, namely, the need to machine the extruded extrusion material.